class User {
    String username
    String number //like: QQ id
    String password
    String target // a,b,c,d
    
    static hasMany = [photos: Photo];

    static constraints = {
        username(size: 1..200, blank: false);
        number(size: 1..12, blank: false);
        password(size: 1..8, blank: false);
        target( blank: false);

    }

    String toString() {
        "$username : $number"
    }
}
